Step drill bit set, quality tool for jobs of all sizes Made from high-quality steel Titanium coated to reduce friction and heat 3 sided shanks design in order to prevent slippage when in chuck Two flute design provides faster, smoother and cleaner cuts with each step is clearly labelled with the depth diameter in steps Size: 4-12mm, 4-20mm, 4-32mm Ideal for using to cut holes in a variety of materials including steel, brass, wood, plastic, etc.SpecificationsMaterial: HSS Steel Finish: Titanium Color: Golden Length: 4-12mm Length: Approx. 6.7cm/ 2.64″ 4-20mm Length: Approx. 7.4cm/ 2.91″ 4-32mm Length: Approx. 10.2cm/ 4.02″ The 3 Cutters Come in the Following Sizes: 4-12mm (4mm, 6mm, 8mm, 10mm, 12mm) 4-20mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm) 4-32mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm) NOTE: Please do not use on metal plates that are >3mm thick if using hand drill. Metal plate thickness of 3-5mm is acceptable ONLY on stabilized drill bench. Please apply adequate water cooling while drilling to prevent damage to the drill set.